'their peaks' is a grammatically correct and usable part of a sentence in written English.
For example, you could use it in the sentence: "The climbers slowly scaled their peaks."
Novelists hit their peaks at different ages.
They later fell more than 98percentt from their peaks.
The best ideas are tested by their peaks and troughs.
The market's promise helped drive the shares of the energy traders to their peaks last year.
Commodity prices have declined from their peaks, but generally remain at high levels by historical standards.
Yes, the director, the cinematographer and the screenwriter were all working at their peaks.
Partly, it levels the terrain somewhat for comparisons with Munch's epigones — his valleys meet their peaks.
The proportion of GCSE grades awarded has fallen at all levels from their peaks in 2011.
Both indexes are still more than 56percentt below their peaks.
PETROLEUM prices, though below their peaks of last year, are still lofty.
The view at the top revealed gaunt granite pinnacles with clouds encircling and protecting their peaks.
